In the art of waterbeds, water-filled bladder-like mattresses are supported atop platforms and are retained about their perimeters by vertical frames projecting up from the platforms which normally including head, foot and side boards or retaining walls. To maintain the water-filled mattresses at comfortable temperatures, flat, blanket-type resistance heaters are positioned flat between the platforms and the bottom surfaces of the mattresses. The heaters are supplied with electric current by service cords that extend from the heaters, between the mattresses and platforms, upwardly between the mattresses and the retaining walls, over said retaining walls and thence to power service outlets.
It is common practice to turn the heaters in waterbeds on and off to establish and maintain the mattresses at desired set temperatures. To this end, manually-adjustable thermally-responsive on and off switch means are provided in one of the pair of conductors of the power cords for such heaters. The most common and widely used thermally-responsive on and off switching means provided by the prior art comprises a manually-adjustable on and off snap action-type switch arranged in a large housing or case that can be arranged outside of and remote from its related waterbed structure, away from the large volume of water within the waterbed structure, for obvious safety reasons. The switch is controlled (opened and closed) by a diaphragm-type fluid pressure actuating device connected with an elongate capillary tube that extends from the case and into the waterbed structure, between the platform and mattress, where it is provided with a large bulb. That is, a common bulb and capillary tube is used. The housings for such devices are engaged about their related power cords between the ends thereof.
The great problem with the above noted type of class of control means resides in the fact that the dispositioning of the portions of the power cords extending from the heaters to the housings and dispositioning of the elongate capillary tubes extending from the housings into the waterbed structures create dangerous and unsightly obstructions, are subject to being damaged. They frequently prevent desired convenient and attractive placement of the housings. Irreparable damage to the elongate, exposed and unprotected portions of the capillary tubes of such control devices is the single most common problem and is a problem which is frequently not understood or recognized. When a capillary tube for such control means is damaged and the control means fails to function properly, malfunctioning of the control means is most often attributed to the failure of some part or portion of a controller within the controller housing and/or to an inferior quality of the control means as a whole.
To overcome the above and other undesirable characteristics and features of the above noted common-type or class of waterbed heater control means, the prior art has offered waterbed heaters with pre-set temperature-responsive control switches incorporated in them and have used other, more sophisticated electric or electronic temperature-sensing means in place of the common capillary and bulb-type means. While such diverse and alternate means have worked or shown promise, they have presented unique problems and shortcomings of their own and have, therefore, failed to supplant or become recognized as equal to or better than the first above noted common-type or class of control means.
It has been determined and is readily recognizable that the great majority of shortcomings found to exist in common present day waterbed mattress controllers would be eliminated and greatly reduced if:
(1) the need for and use of bulb and capillary tube units with elongate, freely-extending capillary tubes was eliminated; and,
(2) if the controller housings were to be made adequately waterproof and sufficiently small that they could be safely and conveniently placed within related waterbed structures, as between a retaining wall thereof and the mattress, rather than between the ends of an elongate, slack and unrestrained portion of the heater power cord extending freely from within and outside of the bed structure.